A common feature in robotic vacuums are main and side brushes. The purpose of a brush is to achieve the cleaning of debris in the work environment. However, since the brushes spin, an immense issue that has arisen is the entanglement of the brushes with electrical cords, cables, wires and the like in the work environment. As the brush spins, the electrical cord or wire will be caught up in the spinning mechanism and become stuck around the spinning brush thus disabling the brush as well as the robotic vacuum itself. In turn, an operator has to come and detangle the wire from the mobile robot which is undesirable.
In prior art, the amount of current generated by a separate brush motor has been used to detect entanglement with an obstruction as the power required and the current generated in rotating the brush would increase if entanglement occurred. Once entanglement is detected the brush is programmed to stop and reverse direction until the current is below a certain threshold, at which time the robotic device may resume operation. However, an increase in the current generated by the brush motor may occur for reasons other than an entanglement with an obstruction, resulting in false detection of a brush entanglement. For example, when operating on a thick pile carpet the current generated by the brush motor may increase because more power is required to rotate the brush through thick pile carpet. This may trigger the brush motor to stop and the brush to operate in the reverse direction when not needed. A need exists for a more accurate method to identify entanglements on vacuum brushes.